How can I control Keynote with foot pedals? What hardware do I need?

I want to use Keynote while playing guitar, and I want to be able to go forward and backwards with slides, controlling it with some pedals. What devices will let me control Keynote with my feet?

Thanks!

Something like this would seem to work. There's always a diy option. Try a search term such as "control presentation with foot pedals" for more options. Never tried this personally BTW.